Electrically conducting flexible polymeric nanocomposite has been fabricated through wet mixing method where conducting inclusion was acoustically exfoliated pristine graphene nanosheets. Colloidal graphene is the key component here which has been prepared by acoustic cavitation in the presence of macromolecular dispersion. The significance of the method is their green preparation strategy without using any chemical reducing agents and long self-life without drastic sedimentation rate. Thermoplastic poly(ethylene-co-methyl acrylate) was chosen as flexible phase where graphene sheets were distributed to make spatial conducting network architecture. The prepared nanocomposites showed 0.259 S/cm DC electrical conductivity and frequency-independent electroconducting character in higher concentration. The electromagnetic interference shielding effectiveness of the nanocomposites was around 30 dB in 1.0 mm thickness in X-band (8.2-12.4 GHz) frequency range without affecting its mechanical toughness and flexibility. Thus, such pristine graphene-based thermoplastic matrix could be a desirable replacement of metallic shielding materials on the ground of flexible, conducting, lightweight characteristics. [GRAPHICS] .